6. High Pressure Discharge Lamps

6. High Pressure Discharge Lamps Content 6.1 Overview of Low Low- and High High-Pressure Pressure Discharge Lamps 6.2 Spectrum of a Hg Discharge 6.3 T...
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6. High Pressure Discharge Lamps Content 6.1 Overview of Low Low- and High High-Pressure Pressure Discharge Lamps 6.2 Spectrum of a Hg Discharge 6.3 The High-Pressure Mercury Lamp (HP) 6 4 Phosphors for High-Pressure Mercury Lamps 6.4 6.5 The Electrode 6.6 The Electrode Feed Through 6 7 Types 6.7 T off R Reflectors fl t 6.8 Application of HP-Lamps 6.9 The High-Pressure Sodium Lamp (HPS) 6.10 Application of HPS Lamps 6.11 Metal-Halide Lamps (MH) 6.12 Photometric Data in Comparison 6.13 Applications of MH Lamps 6.14 UHP-Lamps p 6.15 New Developments Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 1

6.1 Overview of Low- and High-Pressure Discharge Lamps HID = High Intensity Discharge Hg low-pressure (TL)

Hg high-pressure (HPMV = high pressure metal vapour)

Hg low-pressure (CFL)

Na high-pressure (HPS = high pressure sod.)

Na low-pressure (SOX)

Metal-halide high-pressure (MH)

Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 2

Emissionsspektrum von Hg 6.2 Spectrum of Hg Discharges Energy level scheme of Hg Ionization level (~ 10.4 eV) 10

Schematic emission spectrum of a Hg-discharge at a low pressure [~ mbar] 254

6(3D1) 7(3S1)

5466 5777

6(3P1)

4088 4366

6(3P2)

5

3133 3666

1185

6(1P1)

1185 nm

Level energy y [eV]

7(1S0)

6(3P0)

200

300

400

500

600

 [nm] 0

6(1S0)

Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 3

200

300

500

 in nm

100 lm/W

60

20

600

546 577

3313

408 200

254

1885

5 546 5577

4 408 4436 400

Phosphor P

 [lm/W]]

100

3 313 3366

185

Pressure increase

436

366

254

6.2 Spectrum of Hg Discharges

300

400

500

 in nm

600

Pressure dependence of the lumen output 60 lm/W  Why is this of interest for lamps? Good imaging properties High luminance

20 lm/W 10 bar

Incoherent Light Sources Prof. Dr. T. Jüstel

1 bar

Pressure Chapter High Pressure Discharge Lamps Slide 4

6.2 Spectrum of Hg Discharges Measured spectra of water-cooled capillary mercury discharge lamps P = 25 atm atm..

P = 30 atm. atm.

P = 100 atm atm..

Source: W. Elenbaas, QuecksilberdampfHochdrucklampen (1966) Incoherent Light Sources Prof. Dr. T. Jüstel

P = 150 atm atm.. Chapter High Pressure Discharge Lamps Slide 5

6.3 The High-Pressure Mercury Lamp (HP) Evacuated outer bulb Melting Electrode

Burner (Hg, noble gas = starting Gas, mostly Xe)

Ballast Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 6

6.4 Phosphors for High-Pressure Mercury Lamps 5

Inte ensity [a.u.]

4

3

2

1

0 400

500

600

700

800

Wavelength [nm]

 = 60 lm/W

Ra = 20 Lifetime = 20.000 h Incoherent Light Sources Prof. Dr. T. Jüstel

Blue white light due to the Blue-white lack of red radiation in the emission spectrum Solution: Phosphor! Chapter High Pressure Discharge Lamps Slide 7

6.4 Phosphors for High-Pressure Mercury Lamps 5

Plasma Relativve Intensity [a..u.]

4

3

Phosphor

2

1

0 400

Suitable phosphors (Sr,Mg)3(PO4)2:Sn Mg4GeO5.5F:Mn YVO4:Eu Y(V,P)O4:Eu

500

600

700

Wavelength [nm]

620 nm 660 nm 620 nm 620 nm

Broadband emission Line emission Line emission Line emission

 = 60 lm/W

Ra = 50 Lifetime = 20.000 h Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 8

800

6.4 Phosphors for High-Pressure Mercury Lamps Sn2+ , Mn4+ phosphors as UV  Red converter

Luminescence spectra of (Sr,Mg)3(PO4)2:Sn 1,0

max = 620 nm

QE254 = 79 % RQ254 = 5% x = 0.549 y = 0.426 LE = 150 lm/W

Re elative intensity

0,8

0,6

0,4

0,2

Intensiity

0,0 100

Emission spectrum Excitation spectrum Reflection spectrum 200

300

400

500

600

700

800

Sample U2024

W Wavelength l th [nm] [ ]

Luminescence spectra of Mg4GeO5.5F:Mn Emission spectrum Excitation spectrum Reflection spectrum

1,0

Relative intensity

0,8

[nm]

Problem: Low lumen equivalent i off these phosphors Incoherent Light Sources Prof. Dr. T. Jüstel

max = 658 nm

QE254 = 81 % RQ254 = 7%

0,6

x = 0.713 y = 0.287 LE = 80 lm/W

0 0,4

0,2

0,0 100

200

300

400

500

Wavelength [nm]

600

700

800

Sample U601

Chapter High Pressure Discharge Lamps Slide 9

6.4 Phosphors for High-Pressure Mercury Lamps YVO4:Eu3+ phosphors - Thermal behavior Excitation spectra of YVO4:Eu U737025C U737075C U737150C U737200C U737250C U737300C U737330C

Emission in ntensity [a.u.]

0,25

0,20

0,15

0,10

0,05

0 00 0,00

monitored at 619 nm 250

300

350

400

Wavelength [nm]

Emission spectra of YVO4:Eu U737025C U737075C U737150C U737200C U737250C U737300C U737330C excitation at 300 nm

Emission intensity [a.u.]

80000

60000

40000

600

650

700

integral 254 nm exc. Integral 300 nm exc. Integral 350 nm exc.

7 6 5 4 3 2 1 0 0

50

100

150

200

250

300

The luminous Th l i efficacy ffi under d UV-A UV A excitation it ti increases i up to about 300 °C Reason: Increase in spectral overlap 750

Wavelength [nm]

Incoherent Light Sources Prof. Dr. T. Jüstel

350

Temperature [°C]

20000

0 550

Luminescence intensity as a function of t temperature t and d excitation it ti wavelength l th

8

Relative em mission intensity

0,30

Chapter High Pressure Discharge Lamps Slide 10

6.5 The Electrode Hg low-pressure

Hg high-pressure

0.5 cm

1.0 cm

36 W I = 0.36 A

400 W I=4A

Tungsten + emitter BaO / SrO / CaO

Tungsten + emitter BaO / SrO / Y2O3 / ThO2

T = 1350 K

T = 2000 - 3000 K

Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 11

6.6 The Electrode Feedthrough Problem: Different thermal expansion coefficients Quartz (1000 °C) Plasma

Tungsten

Incoherent Light Sources Prof. Dr. T. Jüstel

Very thin Mo- or Nb-foil

SiO2 W Mo

= 0.5*10-6 K-1 = 4.3*10-6 K-1 = 2.8*10-6 K-1

Molybdenum

Chapter High Pressure Discharge Lamps Slide 12

6.7 Types of Reflectors Parabolic reflectors

Elliptical reflectors

y = x2

Focal point (light source)

An ellipse has two focal points

Only when the light source is point like

HID lamps HID-lamps

Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 13

6.8 Application of HP-Lamps In street lighting (outdoor lighting)

 = 60 lm/W

Ra = 50 Lifetime = 20.000 h P = 100 W - 2000 W Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 14

Na low-pressure Lamp (0.01 mbar)

300

200

400

500

600

 in nm

 in lm/W

Pressure increase

700

589 nm

589 nm

6.9 The High-Pressure Sodium Lamp (HPS)

Na high-pressure Lamp (100 mbar)

300

400

500

600

 in nm

700

Pressure dependence of the lumen output 120

10 bar Incoherent Light Sources Prof. Dr. T. Jüstel

1 bar

Na-pressure Na pressure Chapter High Pressure Discharge Lamps Slide 15

6.9 The High-Pressure Sodium Lamp (HPS) Problem: Na reacts at high temperatures with the quartz glass wall 4 Na + SiO2  2 Na2O + Si Solution: Transparent, high temperature resistant material, which does not react with Na

Crystal

Al2O3-ceramics (corundum): MgO, CaO, B2O3-Additives (DSA = densely sintered alumina)

20 m

Polycrystalline structure Pressure, 1200 °C

Nb or Mo Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 16

6.9 The High-Pressure Sodium Lamp (HPS)

589 nm n=3 n=2 n=1

Incoherent Light Sources Prof. Dr. T. Jüstel

Widening of the Na-line and selfabsorption leads to a spectral hole in the emission spectrum at around 589 nm pNa = 150 mbar (saturated) pHg = 1000 mbar (buffer gas) pXe = 100 mbar (start gas)  = 90 - 120 lm/W Ra = 20 – 50 (p (pressure dependent) p ) Tc = 1930 K (589 + x) nm (red-shift) (589 - x) nm (blue-shift)

Chapter High Pressure Discharge Lamps Slide 17

6.10 Application of HPS Lamps Architectural and street lighting

Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 18

6.11 Metal-Halide High-Pressure Lamps In 451

Tl Na 535 589

Filling: NaI - TlI - InI SnBr2 - SnI2 NaI - DyI3 (SSTV) NaI - ScI3 (automobile headlight) Goal: High  & color rendering

SnBr/SnI-molecule emitters

DyI-molecule emitters

Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 19

6.11 Metal-Halide High-Pressure Lamps HPI (High Pressure Iodide) lamps

451 nm (In) 535 nm (Tl) 589 nm (Na)

Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 20

6.11 Metal-Halide High-Pressure Lamps Spectrum of a MH lamp 0.30

Tl 0.25

Hg / NaI / TlI / DyI3 / Ar P = 75 W

V

Na

I [W W/nm]

0 20 0.20

Hg

Prad / P  60 % Prad,vis rad vis / P  33 %

Na

0.15

0.10

Hg 0.05

0.00 350

atomic line and molecular radiation 400

450

500

550

600

650

700

750

  [nm] Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 21

800

6.11 Metal-Halide High-Pressure Lamps Filling of metal halide lamps Lamp p starting g (starting g ggas) Noble gases: Ar or Xe (xenon lamps) → Penning-effect Radioactive substances: 85Kr, 147Pm Operating voltage • Hg • Trend towards the substitution of Hg (environmental aspect) → Zn Light emission • Hg • Me-halides (Me = Na, In, Tl, Sc, Sn, Dy, ...)

Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 22

6.12 Photometric Data in Comparison HP (Hg)

HPS (Na)

MH

Improvement -

 (lm/W) 60

Ra 20

Color temperature Tc [K] 6000

+ phosphor

60

50

3800

-

60 - 130

20

2000

Xe-pressure

80 - 150

20

2000

Na-pressure

60 - 90

60

2200

HPI (NaI-TlI-InI) 70 - 80

70

3800 - 4200

SnBr2-SnI2

70

90

NaI-DyI3

75 - 80

90

3800 - 5600

NaI-ScI3

80 - 90

75

3600 - 4200

Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 23

6.13 Applications of MH Lamps HPI (NaI-TlI-InI)

Street lighting Architectural lighting Sports field lighting

Tin

Older type of lamp is replaced by MH

NaI-DyI3 NaI ScI3 NaI-ScI

Sports field lighting Shop lighting Studio-stage-TV (SSTV) Automotive headlights

NaI ScI3 + Hg + Xe (blue) NaI-ScI

Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 24

6.13 Applications of MH Lamps SSTV market k t = St Stage-Studio-TV St di TV Reflector

Spherical mirror

f

Fresnel-lens

Farbtemperatur = 5600 K Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 25

6.13 Applications of MH Lamps In the „beamer“

Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 26

6.13 Applications of MH Lamps Construction of a beamer A projector is actually a slide projector (diascope)!

Lamp at the focal point in a parabolic reflector

Collecting lens

Slide

In a beamer the slide is replaced by a small LCD screen or by a DMD ((Digital g Mirror Device)) Incoherent Light Sources Prof. Dr. T. Jüstel

Projection screen

Chapter High Pressure Discharge Lamps Slide 27

6.13 Applications of MH Lamps Operating principle of a LCD (Liquid Crystal Display) LCDs are based on liquid crystals, which rotate the polarization plane of polarised light by a rotational angle ά

Polarizer-foil P Liquid crystal cell (with ITO) Analyzer foil (perpendicular to P) U

Pixel on for U = 0 Pi l off Pixel ff for f U>0

Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 28

6.14 UHP-Lamps Requirements for light sources for projectors • If possible punctual  A lot of light from a small volume • High luminance (light density )  High Hg-pressure

400

546 n nm 577 nm m

436 nm m

408 nm

UHP = Ultra High Pressure (Performance)  Approx. 200 bar Hg, electrode separation ~ 1 mm  Strong pressure-broadened lines of Hg

500

Incoherent Light Sources Prof. Dr. T. Jüstel

600

700

800 Chapter High Pressure Discharge Lamps Slide 29

6.14 UHP-Lamps Components of UHP-Lamps

Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 30

6.14 UHP-Lamps Design of UHP-lamps

Description of UHP-lamp by • Chemical equations Vapor pressure of metal halides Disintegration of the metal halides in the plasma •Temperature distribution in the plasma Energy balance Loss via radiation Loss due to chemical energy Loss due to heat Convection (flow)

Heat conduction

• Convection equation = Navier-Stokes-Equation 

 2h  2h 0  2 2  x  y

Potential : h  z 

u w

• Energy balance of the electrodes and the wall Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 31

6.14 UHP-Lamps

Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 32

6.15 New Developments Sulfur lamp: In 1990 the first discharge lamp based on a molecular sulfur discharge (S4 – S8) was develop

The energy coupling into the discharge takes place by means of a microwave generator (magnetron), g ( g ), because electrodes can not be used Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 33

6.15 New Developments S lf lamp: Sulfur l To T generate t a very large l luminous l i flux fl

Typical operating parameters Input power: 1.400 W Ball diameter: approx. 30 mm Luminous flux: 135000 lm Color temperature: 5700 K Starting time: 25 s Lifetime (lamp): 60.000 h Lifetime (magnetron): 20.000 h Light output: 95 lm/W

Light source with extremely high light output, about 140000 lm (~ 40 fluorescent tubes) and (almost) pure-white light (emission band of S8, …. , S2 molecules) Efficiency: Problems:

Similar to fluorescent lights (thus 90 - 100 lm/W) EMC and lifetime of the microwave generator

Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 34

6.15 New Developments S lf lamp: Sulfur l Mechanism M h i off light li ht generation ti  Emission E i i from f molecules l l , e.g. S2

C. W. Johnston, Transport and equilibrium in molecular plasmas: The sulfur lamp, Technische Universiteit Eindhoven, Eindhoven 2003 Incoherent Light Sources Prof. Dr. T. Jüstel

Chapter High Pressure Discharge Lamps Slide 35

6.15 New Developments Substitution of Hg by Zn (e.g. in automotive headlamps) Zn/Ar Discharge

Zn/Ar/metal halide Discharge

1,0

0,8 472

0,6 636 468

0,4

0,2

0,30

Wel = 75 W LE = 280 lm/W x = 0.436, y = 0.387 Tc = 3000 K Efficacy = 85 lm/W  = 0.33 Wopt/Welektr Ra8 = 80

0,25

Emis ssion intensity [a.u.]

Emisssion intensity [a.u.]

481

Wel = 75 W LE = 114 lm/W x = 0.228, y = 0.227 Tc = 34000 K Efficacyy = 20 lm/W  = 0.174 Wopt/Welektr Ra8 = 0

0 20 0,20

0,15

0,10

0,05

Ce3+ Luminescence 0,0 400

500

600

700

File: Zn discharge lamp (60-75-90W)

Wavelength [nm]



Energy efficiency Ra Incoherent Light Sources Prof. Dr. T. Jüstel

800

0,00 300

400

500

600

700

Wavelength [nm]

Zn-Ar 20 llm/W /W 17% 0

800

File: Zn discharge lamp (60-75-90W)

Zn-Ar-metal halide 85 llm/W /W 33% 80 Chapter High Pressure Discharge Lamps Slide 36

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